Browsing by Author "Chang, Chungliang"

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Effect of plasma processing gas composition on the nitrogen-doping status and visible light photocatalysis of TiO2
(2007-10-25)
Chen, Chienchih
;
Bai, Hsunling
;
Chang, Chungliang
;
環境工程研究所
;
Institute of Environmental Engineering
The atmospheric pressure plasma enhanced nanoparticle synthesis (APPENS) process is applied to produce nitrogen (N) doped titania (TiO2) photocatalysts. With TTIP (titanium tetraisopropoxide; Ti(OC3H7)(4)) and water vapors as precursors, the effect of plasma and annealing gas composition on the N-doping status is identified by a cross comparison of the chemical shift of N atoms with those of Ti and O atoms. The activities of various types of N-doped photocatalysts are evaluated via the conversion of isopropyl alcohol (IPA). The results show that the N-doped TiO2 particles with O-x-Ti-N-y and -(NO) dopants are produced via N-2 plasma gas followed by air or N2 annealing gases. They have better visible and UV photocatalytic activities compared to the pure TiO2 photocatalysts prepared under O-2/Ar plasma and annealing gases. On the other hand, the N-doped TiO2 photocatalyst produced under N-2/O-2/Ar plasma gas and then annealed with pure N2 gas tends to have an additional dopant of -(NO2), but its photocatalytic activity is even worse than those of the pure TiO2 photocatalysts. The results reveal that the Ox-Ti-Ny and -(NO) dopants may have positive effects on the visible light photocatalytic activity while the -(NO2) dopant tends to have a negative effect on the visible light photocatalytic activity.
Preparation of N-doped TiO2 photocatalyst by atmospheric pressure plasma process for VOCs decomposition under UV and visible light sources
(2007-06-01)
Chen, Chienchih
;
Bai, Hsunling
;
Chang, Sue-min
;
Chang, Chungliang
;
Den, Walter
The nitrogen doped (N-doped) titanium dioxide (TiO2) photocatalyst was prepared by the atmospheric-pressure plasma-enhanced nanoparticles synthesis (APPENS) process operated under normal temperature, i.e. the dielectric barrier discharge plasma process. The N-2 carrier gas is dissociated in the AC powered nonthermal plasma environment and subsequently doped into the TiO2 photocatalyst that was capable of being induced by visible light sources. The APPENS process for producing N-doped TiO2 showed a higher film deposition rate in the range of 60-94 nm/min while consuming less power (< 100 W) as compared to other plasma processes reported in literatures. And the photocatalytic activity of the N-doped TiO2 photocatalyst was higher than the commercial ST01 and P25 photocatalysts in terms of toluene removals in a continuous flow reactor. The XPS measurement data indicated that the active N doping states exhibited N 1s binding energies were centered at 400 and 402 eV instead of the TiN binding at 396 eV commonly observed in the literature. The light absorption in the visible light range for N-doped TiO2 was also confirmed by a clear red shift of the UV-visible spectra.